public class ExcludeFieldsAggregation implements AggregationOperation
	private String[] fields;
	public ExcludeFieldsAggregation(String...fields)
		this.fields = fields;
	@Override
	public Document toDocument(AggregationOperationContext context)
		Document result = new Document();
		for (String field: fields) {
			result.put(field,0);	
		return new Document("$project", result);
public class IncludeFieldsAggregation implements AggregationOperation
	private String[] fields;
	public IncludeFieldsAggregation(String...fields)
		this.fields = fields;
	@Override
	public Document toDocument(AggregationOperationContext context)
		Document result = new Document();
		for (String field: fields) {
			result.put(field,1);	
		return new Document("$project", result);
package org.springframework.data.mongodb.core.aggregation;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.bson.Document;
import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
import org.springframework.data.mongodb.core.query.CriteriaDefinition;
import org.springframework.util.Assert;
import org.springframework.data.mongodb.core.aggregation.ExcludeFieldsAggregation;
import org.springframework.data.mongodb.core.aggregation.IncludeFieldsAggregation;
public class LookupPipelineOperation implements AggregationOperation, FieldsExposingAggregationOperation, InheritsFieldsAggregationOperation
	private Field from;
	private Field localField;
	private Field foreignField;
	private ExposedField as;
	private Document lets = null;
	private List<AggregationOperation> pipeline = new ArrayList<>();
	private String[] includeFields;
	private String[] excludeFields;
	 * Creates a new {@link MatchOperation} for the given {@link CriteriaDefinition}.
	 * @param criteriaDefinition must not be {@literal null}.
	public LookupPipelineOperation()
	public LookupPipelineOperation let(String fieldName, String expression)
		Assert.notNull(fieldName, "Field name must not be null!");
		Assert.notNull(expression, "Expression must not be null!");
		if (this.lets==null) {
			this.lets = new Document();
		this.lets.append(fieldName, expression);
		return this;
	public LookupPipelineOperation from(String from)
		Assert.notNull(from, "From must not be null!");
		this.from = Fields.field(from);
		return this;
	public LookupPipelineOperation as(String as)
		Assert.notNull(as, "As must not be null!");
		this.as = new ExposedField(Fields.field(as), true);
		return this;
	public LookupPipelineOperation include(String... fields)
		Assert.notNull(fields, "Fields must not be null!");
		this.includeFields = fields;
		return this;
	public LookupPipelineOperation exclude(String... fields)
		Assert.notNull(fields, "Fields must not be null!");
		this.excludeFields = fields;
		return this;
	public LookupPipelineOperation pipeline(AggregationOperation pipeline)
		Assert.notNull(pipeline, "Pipeline must not be null!");
		if (this.pipeline == null)
			this.pipeline = new ArrayList<>();
		this.pipeline.add(pipeline);
		return this;
	public LookupPipelineOperation pipeline(List<AggregationOperation> pipeline)
		Assert.notNull(pipeline, "Pipeline must not be null!");
		this.pipeline = pipeline;
		return this;
	public LookupPipelineOperation localField(String localField)
		Assert.notNull(localField, "localField must not be null!");
		this.localField = Fields.field(localField);
		return this;
	public LookupPipelineOperation foreignField(String foreignField)
		Assert.notNull(foreignField, "foreignField must not be null!");
		this.foreignField = Fields.field(foreignField);
		return this;
	 * (non-Javadoc)
	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.
	 * springframework.data.mongodb.core.aggregation.AggregationOperationContext)
	@SuppressWarnings("deprecation")
	@Override
	public Document toDocument(final AggregationOperationContext context)
		context.continueOnMissingFieldReference();
		if (this.excludeFields != null)
			pipeline.add(0, new ExcludeFieldsAggregation(this.excludeFields));
		if (this.includeFields != null)
			pipeline.add(0, new IncludeFieldsAggregation(this.includeFields));
		Document lookupDoc = new Document();
		lookupDoc.append("from", from.getTarget());
		if (this.localField!=null)
			lookupDoc.append("localField", localField.getTarget());
		if (this.foreignField!=null)
			lookupDoc.append("foreignField", foreignField.getTarget());
		if (lets != null && !lets.isEmpty())
			lookupDoc.append("let", lets);
		if (this.pipeline != null && this.pipeline.size() > 0)
			lookupDoc.append("pipeline", pipeline.stream().map(op -> op.toDocument(context)).collect(Collectors.toList()));
		if (this.as != null)
			lookupDoc.append("as", as.getTarget());
		return new Document(getOperator(), lookupDoc);
	@Override
	public String getOperator()
		return "$lookup";
	@Override
	public ExposedFields getFields()
		return ExposedFields.from(as);